In the prior art, the buckling device of a scanning head serves to prevent any damage from the movement of a scanner during transport. Therefore, a safety lock is installed on the scanner for locking the scanning head to prevent shift. After transport, the lock must be released for normal operation. However, after the manufacturer assembles a finished product, it is locked for packaging. The user often does not know to unlock the lock, so that the scanner cannot be operated. This often causes a user to conclude that the scanner is defective and requests maintenance service by phone or returns the scanner. Moreover, after starting up the scanner, the motor may be left operating continuously such that it is destroyed. Therefore, the prior art buckling structure of a scanner with a safety lock is not suitable in practice, and an improved design is much needed.